


Filled Up

by Fangirl_on_a_bicycle



Category: Steven Universe (Cartoon)
Genre: (jasp is their Special Guest), (which is amedot), Alien Biology, Double Penetration, Established Relationship, F/F, Plot What Plot/Porn Without Plot, Porn with Feelings, Tentacles, Threesome - F/F/F, tentadicks, xenogenitals
Language: English
Status: Completed
Published: 2018-09-26
Updated: 2018-09-26
Packaged: 2019-07-17 19:46:40
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,583
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/16102556
Author URL: https://archiveofourown.org/users/Fangirl_on_a_bicycle/pseuds/Fangirl_on_a_bicycle
Summary: Jasper and Peridot both love Amethyst...at the same time.





	Filled Up

**Author's Note:**

  * For [malafight](https://archiveofourown.org/users/malafight/gifts).



> The other night I was talking to malafight and said, "Man, I need to write a fic with tentadicks in it at some point," and then remembered a fic I'd only written a tiny part of, and realized "Oh wait this could easily be tentadicks" and then I spent two nights writing and editing. Phew. This fic is gifted to them mostly 'cause they're awesome, but also because I hadn't managed to write anything substantial for so long that I was starting to get worried, and our long conversations finally shook something loose in my brain enough to write, for which I'm extremely grateful. <3
> 
> If you've not familiar with the idea of tentadick gems, I put a short explanation and a link in the end notes! 
> 
> This fic takes place in some magical future point in which Jasper is unbubbled, uncorrupted, and getting along with everyone; and Peridot and Amethyst are in a relationship. 
> 
> Last but not least, a grumpy disclaimer: Amethyst and Jasper were manufactured. They don't have parents, don't have genetics, and therefore are not sisters; one moment of recognition of their shared origins (before we met the famethyst) does not siblings make. Dumbass "but they're sisters!" comments will be deleted. Okay? Okay.

“You can’t shapeshift a bigger pussy.” 

“Why the fuck not?” Amethyst frowned. 

Jasper shrugged. “If you’ve shifted a deeper vagina, and you lose your shift too fast when you orgasm, at the very least it’ll hurt but you could poof. No, listen to me. I’m serious. If I suspect you’ve shifted yourself a bigger vagina, I’m not gonna evert all the way. Got that?”

“...Fine.” 

Peridot spoke up. “Good! We all need to feel comfortable and safe if this is going to work.” She was starting to think maybe this wasn’t a great idea after all. But they’d both been so enthusiastic before…she looked at Amethyst. Her arms were crossed over her chest and she was looking away. But by now she could read Amethyst as easily as the marks on an exit hole. 

“Amethyst, I’m sure Jasper isn’t doubting your skill at shape-shifting. She just doesn’t want anyone to get hurt, even by accident. This is us doing a nice thing for you, because we both enjoy doing nice things for you, and neither of us will enjoy it if you hurt yourself out of some misplaced pride.”

“Psht, like you’re not both excited to give it to me at the same time.” 

Jasper smiled. “I’m definitely excited to ‘give it to you.’ Fully everted or not, I wanna see whether you can handle what I’ve got.” 

Amethyst slowly grinned back. “I dunno, can you handle how hard my pussy can squeeze when I come?”

Peridot rolled her eyes. “Stars above! You quartzes are all the same: vulgar and constantly horny.” 

Amethyst gently bumped against her. “And you like it, or we wouldn’t be having this conversation.” 

Peridot put her nose in the air. “I have never once denied my attraction to quartzes and I’m not ashamed of it, so you can’t use that to impugn me.”

 

Amethyst was familiar with the experience of being in her own room, on top of a mattress on the floor, with Peridot whimpering into kisses while she groped and squeezed Amethyst’s tits. She was less familiar with pulling back and looking down and to see Jasper’s arms around Peridot’s thighs, her head between Peridot’s legs, sucking and licking gently at the little bud hidden between her labia. It always took more time and stimulation for Peridot to evert, which meant more often than not it was Amethyst who fucked Peridot, both of them tending towards impatience together, just wanting one of them to be inside of the other now now _now,_ and Peridot not everting until she was so close that it took three slippery pulls of Amethyst’s hand for Peridot to cover both their bellies in sticky come as she shouted.

But now, Peridot looked up at Amethyst with dazed eyes, her hands drifting into Jasper’s mane, moaning out loud in that unashamed way she always did. 

“Oh yes, right there, like that, oh Jaaasper.”

Amethyst grinned down at Peridot, then cupped one of her small breasts and gently pinched a nipple, making Peridot squeak and Jasper glance up from what she was doing, her eyes smiling even with her mouth busy. 

Peridot’s eyes closed and her sounds got slower and deeper and Jasper’s head was moving slower, up and down, drawing Peridot’s tentacle out bit by bit as it chased after the heat of Jasper’s mouth. Amethyst’s jaw dropped. That was, quite possibly, the hottest thing she’d ever seen in her life. Jasper’s thick lips wrapped around Peridot’s everted tentacle as she gave one long final suck from base to tip.

Jasper sat up, wiping her mouth, and Peridot whimpered at the loss of contact, her hands moving towards her tentacle. But she just held it at the base with a gentle squeeze. It really wasn’t very big--which was sort of a blessing this time. 

“You gonna be able to stick that in my ass without coming immediately?”

Peridot eyes opened up at her. “Yeah, I think so,” but she didn’t look sure. 

“You’d better, after I spent all that time getting it to stop being so shy,” Jasper griped. 

Amethyst laughed. “You enjoyed that, don’t pretend you didn’t.”

“I didn’t say I didn’t enjoy it. But anyway, how are you doing?”

Peridot sat up a little to turn towards her.  Two sets of eyes on Amethyst, and that’s when she noticed she was idly stroking her own everted tentacle, and her face heated. This was the wrong time to suddenly be embarrassed, shit. 

Amethyst cleared her throat, then put her hair up in a messy bun before putting her hands behind her and leaning back, bending her knees and spreading her legs. She reached down and slid her fingers against her labia, showing off how wet she was, almost entirely just from watching Jasper suck off her girlfriend. It felt nice to touch herself, moving her hand back to her tentacle. Even better was the looks of desire on both Jasper and Peridot’s faces; Peridot’s a familiar look of awe and delighted anticipation, Jasper’s a more feral hunger that made Amethyst’s tentacle jerk in her hand. Jasper saw it and smiled with sharp teeth. Naked Jasper was something else--her muscles visible beneath a little padding, her breasts round and high, and her own everted tentacle between her legs, proportional in size to the rest of her, with a stripe of red slashed across it and flashing out from under Jasper’s hand slowly stroking up and down in time with Amethyst’s own. 

Jasper moved towards her on her knees and lifted Amethyst to standing before moving in to kiss her. 

Where Peridot’s kisses tended towards earnest if a little sloppy, Jasper’s felt careful and controlled. She knew exactly what she was doing and how to get the reaction she wanted, including wrapping an arm around Amethyst’s lower back and getting a handful of plump backside just before sliding another one of her big hands up a thigh and then over her tentacle, pressing it against Amethyst’s belly, just enough to make Amethyst gasp and moan into the kiss, and she could let her legs get wobbly because Jasper had her. Jasper made her feel safe like this. 

And right now, Jasper put her mouth close to Amethyst’s ear.

“You ready for us?” Jasper growled. She pulled back and looked at her with that feral grin again. Just over her shoulder she could see Peridot, watching them with her eyes wide and her tentacle still out in her hand.

“Oh, fuck yes, I’m ready.”

 

Jasper was on her back, and Amethyst was kneeling on top of her, her knees digging into Jasper’s lower abs. It didn’t hurt, not really; Amethyst might have been heavy for her height but Jasper was build too solidly. 

Besides, any discomfort was wiped out by the image of Amethyst’s face warring between determination and arousal, closing her eyes and biting her lip and furrowing her eyebrows as she leaned on her hands and slowly guided herself down onto Jasper’s tentacle; as well as the sensation of her vagina fluttering around it as it eagerly adapted to the intrusion. Jasper rested her hands on Amethyst’s hips, not pushing at all, just supporting. 

Jasper had braced herself to pull part of her tentacle back in or meet the difference with one hand. But Amethyst slipped down the last few inches, making them both gasp, and it was all inside of her, and she let her legs move down, squeezing on either side of Jasper’s hips, her feet still a fair distance from the floor.

Quietly, from behind Amethyst, Jasper heard Peridot whisper “oh, golly.” Peridot must have been standing and watching between Jasper’s open legs. Amethyst smiled and opened her eyes to look at Jasper before closing them again. 

“Told you I could do it.” She shivered and panted and looked focused again. “Don’t move yet, though.” 

Jasper stroked at the bottom of Amethyst’s tummy pudge with her thumbs, trying to distract herself from how badly she really did want to move now that she was inside of Amethyst. She was so hot and slick, almost sucking Jasper into her. Amethyst’s forgotten tentacle twitched and the tip drooled out a drop of precome that ran down until it disappeared where their bodies were joined. 

Just when Jasper thought she’d go mad, Amethyst rocked forward and back, just barely, just enough for Jasper to move inside of her, and Jasper grunted and tightened her grip on Amethyst’s hips just as Amethyst muttered, “Oh fuck, that’s good.”

Amethyst caught a rhythm, not moving up and down so much as rocking, and Jasper caught onto it and moved with her, and Amethyst let loose a string of colorful human curses, heavily littered with _fuck_ and _yes,_  and looked down at Jasper with her eyes half-shut. 

After a few moments, just as Jasper wanted to pick up the pace, there was movement between Jasper’s thighs and a green hand slid down Amethyst’s side, and Amethyst slowed down and smiled and turned slightly towards Peridot still standing behind her. Oh, right.

“Feeling left out?” 

“Only a little. And not for long. Jasper, can I use some of your fluids as lube? You’re making a lot more than I do.” 

“Yeah, that’s fine.” Anything to get back to fucking Amethyst, gently or not. 

A swipe up one side of her labia that bordered on ticklish, then Amethyst leaned forward a little with her face still turned away before she hummed in pleasure and fluttered around Jasper again. 

Jasper tightened her hands on Amethyst’s hips. “Peridot’s not in you already, is she?”

“N-no, she’s just, she’s just touching me.”

“I _have_ fucked Amethyst in the ass before, Jasper. And it’s not as fun if I just shove myself in there, I need to warm her up a little first.”

Amethyst still leaned forward, but she turned back to face Jasper and started rocking again, her face a bit less composed than before. Peridot did another swipe of Jasper’s labia, and something barely moved inside of Amethyst, who gave a full-throated moan. 

“That’s just my finger, Ame.”

“Oh, god, Peri, I want it right noooow.” 

“Okay, okay, hold still for a second.” 

It took so much effort for Amethyst to stop moving that she was digging her fingernails into Jasper. Peridot’s legs brushed against Jasper’s thighs as she moved forward so she spread them a little further apart. 

“Oh god oh god oh god oh god Peri yes yes yes.” Amethyst’s back arched, and that’s when Jasper became aware of how thin the wall between Amethyst’s pussy and ass was, as she felt Peridot’s smaller tentacle sliding in against her own, just on the other side. Peridot’s hands were now on Amethyst’s waist, just above Jasper’s.

“How are you doing?”

“I’m so full, fuck, it’s-- _nnguh,_ it’s perfect.”

“Please start moving, or I think I’m going to shatter,” Jasper panted through gritted teeth. 

Amethyst tried, but she was too overwhelmed, her legs shaking, her tentacle drooling and twitching. So Jasper used the grip she had on Amethyst’s hips to move her back and forth again, and there it was--Amethyst’s slippery heat pulling her in, and Peridot’s tentacle pressing against her almost as if it was reaching for her, and all three of them moaning nearly in unison. 

There was some arrhythmic pushing and pulling until they figured out what worked for all of them, Jasper and Peridot mostly taking Amethyst’s lead and following the sound of her cries. Her head was thrown back, her mouth open, noisier than Jasper and Peridot put together, and every time she drew in breath there was the slick sound of two gems sliding in and out of her and their gasps and groans of their own pleasure. 

Amethyst was beautiful like this, so unselfconscious and so trusting. They both were, Jasper remembering Peridot’s face when her entire tentacle was in Jasper’s mouth. They both wanted her to be a part of this, they both wanted to share this with her, even after everything before. It was an amazing feeling.

Jasper must have slowed down slightly while thinking about it, because Amethyst squeezed Jasper with her thighs impatiently, and Jasper grinned and started fucking up into her in earnest; while not moving as much as she normally would because she didn’t want to dislodge Peridot, whose tentacle was pressing against her own so wonderfully, and whose sounds were even better when mixed with Amethyst’s. 

It was still enough to make Amethyst’s breasts and belly jiggle and bounce, and now mixed into all their previous noises was the _slap! slap! slap!_ of their flesh meeting, and that was a very good sound as well.

 

Amethyst was so full, Peridot’s little cries and gasps and Jasper’s pants and grunts in time with them filling her up, grounded by the two pairs of hands keeping her steady, as they both pushed in and out of the deepest parts of her, and she pulled them back in, over and over, she was so greedy, she wanted all of them, she needed them, she needed this, to be so full of both of them, so full of the gems who loved her enough to do this for her, to make her filled up until she could never be empty or wanting again, and she was almost there, almost there, _almost--_

 

Peridot thought she’d heard all of Amethyst’s sex noises by now: her grunts and curses and groans, or best of all, Peridot’s own name; shouted and slurred and commanding and pleading.  

These sounds were new: reedy, wordless, desperate, almost keening, broken whimpers and high-pitched whines. Amethyst’s bangs were stuck to her face with sweat. Her toes curled and relaxed over and over. Amethyst was trembling, lost to anything but the two of them thrusting into her; her back arched to get the angle she wanted.

Peridot was amazed that she’d managed not to come in Amethyst yet. But this had to be good for Amethyst, and putting her first and thinking about her made it easier; but she ached with how badly she wanted to come. 

Jasper’s stupidly huge tentacle rubbing at her own-- _inside_ of Amethyst!--wasn’t helping matters. Amethyst was already tight when penetrated this way, which is why they both enjoyed it on occasion; but this was something else entirely. The softness of Amethyst’s ass and the way it moved and sounded when Peridot’s thighs smacked into it weren’t helping either. 

But then Amethyst started kicking her legs, and Peridot knew what she wanted, and it was a relief to be able to give it to her. 

She leaned in and took one hand off Amethyst’s waist to reach towards her tentacle, which was moving and twisting, looking for what it needed. It squeezed itself around Peridot’s hand at first, tight enough to nearly hurt, but when Peridot wrapped her hand around the base of it and started sliding up, it let go and stiffened mostly straight, as the rest of Amethyst convulsed and she shouted, and then Amethyst was trying to fuck into Peridot’s fist despite Jasper’s grip on her, and Peridot moved her other arm around Amethyst, hugging her with one arm while jerking her off with the other, and still sliding in and out of her ass. 

Amethyst’s chest was heaving, her noises going up in pitch, as Peridot swiftly moved her hand up and down Amethyst’s tentacle, tighter on the downstroke the way she liked best, slopping her copious precome where it hadn’t already pooled on Jasper or run down her sides. Peridot wished she could see their faces, but focused on keeping the rhythm. Jasper’s thighs were shaking on either side of her but she seemed as determined to see this through as Peridot was. 

Amethyst’s whole body went rigid at the same time that she clamped down, so unbelievably tight, Peridot’s eyes rolling back from the force of Amethyst’s climax, and Jasper’s ragged inhale was the only thing either of them heard for a long second. 

Amethyst was nearly screaming, pulsing around them, pulling at them, her tentacle throbbing in Peridot’s hand as she ejaculated, and Peridot came with relief, barely holding on to Amethyst as her own tentacle spurted inside of her until come leaked out around Peridot’s weakening thrusts, and she had no idea how much of the hot fluid running down her legs was from her own pussy and how much of it was leaking from Amethyst’s ass.

A third option presented itself when she heard Jasper moan so loud and deep it vibrated inside of Amethyst, and Jasper’s spasms felt so good even secondhand that Peridot almost felt like she was coming again. Amethyst still wasn’t done, writhing on top of Jasper and into Peridot’s hand, still throbbing and convulsing for several seconds before she stopped, and she nearly collapsed against Peridot, who was suddenly standing in rather a lot of come, the majority of which wasn’t her own. She nearly fell as she tried to support Amethyst’s weight, and in the process her tentacle slipped out of Amethyst entirely and Amethyst whined at the loss.

“Wait, hold on,” Jasper gently pulled Amethyst towards her to down to lie on her chest, rubbing Amethyst’s back reassuringly for the few seconds it took for Jasper’s tentacle to slide out along with an impressive surge of come. Amethyst made one last small plaintive sound, as if she didn’t want to let it go. 

Jasper carefully turned so Amethyst was lying down, cradled in Jasper’s arm, and Peridot quickly moved towards them while trying not to slip and fall; she had to see Amethyst. 

Amethyst looked so tired, and of course sweaty. But she was still beatific and glowing with satisfaction, and smiled weakly up at Peridot. 

“Aw, you look so worried, Peri. It's okay, I’m fine.”

“I know, but--” and she leaned down and cradled Amethyst’s face in her hands and kissed her mouth, once, no twice, and brushed the hair off her face, and kissed her cheek for good measure, and then sat down and grabbed one of Amethyst’s hands, before looking up at Jasper, who was lying on her side and looking at them with amusement.  

“How are you doing?”

Jasper looked nearly as weary. “Great, actually. Just tired. Dunno why you’re so energetic.”

“Peridot is sometimes like this after sex.”

“Peridots in general tend to find sexual activity doesn’t tire them. I’m still not sure if that was an intentional part of our design or not. In fact, sometimes orgasms clear my mind for--”

“Peridot,” Amethyst interrupted. “We can talk about this later when me and Jasp ain’t so tired.”

“Oh! Sorry. I’ll put my energy to good use. Be right back.”

Peridot fetched the basin of water and the stack of towels they’d set aside, and came back to Jasper and Amethyst lying on their sides facing each other, already almost dozing off, and Peridot took a moment to look at them. They were were nearly a matched set, in their own way. One of the largest quartzes ever made, curled protectively around one of the smallest; their lives a fascinating study of equals and opposites, and here they both were, loving and kind to each other after all they’d been through. It was enough to make Peridot a little over-emotional, thinking about the different ways she cared for and loved them both while they loved and cared for each other.

Right now it was time to care for them in a more concrete way, by helping them clean up. There really was quite a lot of sticky gooey mess. But Amethyst didn’t seem any worse for wear other than being a little sore, wincing slightly as her tentacle slowly retreated. Jasper mostly took care of herself and wiped what she could off the mattress, while Peridot took her time with Amethyst, who let Peridot fuss over her and gave her a sleepy indulgent smile and some kisses in return. Once they were all done Peridot took it all away and came back with some clean blankets and pillows.

 

None of them bothered to phase their clothes back on. Instead, the moment a clean blanket was down, Jasper lay on her side and Amethyst let Jasper pull her in so they were spooning, and Jasper started stroking her hair. Peridot seemed to think this was a genius idea and soon wiggled back against Amethyst so she was sandwiched between them. She kissed the back of Peridot’s neck and wrapped an arm around her waist, and Peridot relaxed with a sigh. So much for Peridot’s post-sex energy. 

They all just spent a moment savoring that particular kind of exhausted, satisfied peace. 

Amethyst slowly realized: she was still full. Just not in the same way. Here she was between two gems who cruel to her, once upon a time--and now here they were, loving her instead, just as she was. 

“Hey, you guys. I just wanna say thank you, y’know, for today.”

Jasper chuckled a low rumble and kissed the top of her head. “We enjoyed it, too, y’know.”

Peridot squeezed Amethyst’s hand. “Yes, it was definitely pleasurable for us as well.” 

“I know that, but--it, it still means a lot to me. So, thank you.” 

They both murmured a “you’re welcome.” Peridot pulled up Amethyst’s hand from her waist and kissed it and put  it back. Amethyst smiled to herself and hugged Peridot, and soon they were all asleep. 

 

 

 

**Author's Note:**

> Tentadicks! 
> 
> The idea is that gems all have vulvas/vaginas, but if you get them aroused enough their clit swells up and slides out ("everts"), and it's like a penis-sized tentacle that they can use for anything you'd want to use a penis for. There's all kinds of variations on the theme floating around, and they're all a lot of fun. (I'm told the concept was originally popularized by the Homestuck fandom.) 
> 
> A short but sweet explanation of tentadicks, which is fairly close to the one I'm using here, explained in comic form with Jasper and Pearl (NSFW, obviously): https://jaxxxker.tumblr.com/post/169014876562/woohoooo-gemitals-a-few-of-you-asked-and-a-few
> 
> ("tentadicks" is not a canonical (aka searchable) ao3 tag yet, though; which I find odd.)


End file.
